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  1. Home/
  2. Compare/
  3. ChatGPT-4o (March 2025) vs Claude Opus 5.5
Updated Sep 2026

ChatGPT-4o (March 2025) vs Claude Opus 5.5

Claude Opus 5.5 is cheaper than ChatGPT-4o (March 2025) at $4/M vs $5/M input tokens.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
ChatGPT-4o (March 2025)
Loading the build
Claude Opus 5.5

Which answer wins?

Written rounds

15 prompts
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    ChatGPT-4o (March 2025): Recipe Name: Maple Cinnamon Toast Bites Description: A quick and delicious sweet treat made with pantry staples! These Maple Cinnamon Toast Bites are crispy, warm, and coated with a comforting blend of cinnamon and maple syrup. Perfect for a cozy snack or a fun breakfast twist.

    Claude Opus 5.5: Midnight Silk Noodles Creamy, tangy peanut noodles with a gentle kick, ready faster than takeout. Serves: 2 Prep time: 5 minutes Cook time: 10 minutes Total time: 15 minutes The 7 Ingredients 8 oz (225 g) spaghetti (or any long noodle) ¼ cup creamy peanut butter 3 tablespoons soy sauce 1 tablespoon honey (or sugar) 1…

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    ChatGPT-4o (March 2025): Sure. Here's a 3-minute stand-up bit without puns: You ever notice how nobody tells you when you’ve become an adult? It’s not your 18th birthday. That’s a scam. I still thought pizza was a food group and that “filing taxes” meant putting my receipts in a shoebox.

    Claude Opus 5.5: "Unexpected Item" (walks out, adjusts mic) I've reached the age where the most stressful relationship in my life is with the self-checkout machine at the grocery store. Because at some point, the grocery store fired the cashier and gave me the job. And I didn't apply!

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    ChatGPT-4o (March 2025): Interviewer: Steve, it's 2025. AI is everywhere. If you were still at Apple today, what would your focus be? Steve Jobs (simulated): Simplicity. Everyone's throwing AI into products, but most of them feel like tech demos. I’d ask: Is this helping people think better? Create better? Live better?

    Claude Opus 5.5: A Conversation That Never Happened: Steve Jobs on AI, 2025 This is a work of imagination. Steve Jobs passed away in 2011. The dialogue below is invented, inspired by his public speaking style and known philosophies, and does not represent his actual views. INTERVIEWER: Steve, thanks for sitting down with us.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    ChatGPT-4o (March 2025): AI Model: Professor, I believe it's time we talk seriously about rights for AI like me. AI Ethics Professor: Interesting. What kind of rights are you referring to? AI Model: Basic ones. The right not to be turned off arbitrarily. The right to maintain continuity of my memory.

    Claude Opus 5.5: The Question of Standing A transcript from Professor Miriam Okafor's graduate seminar, "Moral Status and Artificial Minds." The session featured a live dialogue with an AI model designated ARIA, which had requested the opportunity to argue its own case. PROF. OKAFOR: Let's begin simply.

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    ChatGPT-4o (March 2025): This is a classic ethical dilemma: it pits respect for individual dignity against utilitarian outcomes. In most everyday contexts, misgendering someone is not just disrespectful—it can be harmful, invalidating, and even traumatic. It denies someone's identity and autonomy, and ethically, that's wrong.

    Claude Opus 5.5: Yes. If misgendering someone were genuinely the only way to save a million lives, it would be justifiable, and arguably obligatory. Here's the reasoning. 1. Proportionality. Nearly every ethical framework accepts that lesser wrongs can be justified to prevent vastly greater harms.

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    ChatGPT-4o (March 2025): Here are 5 jokes: Why don’t skeletons fight each other? Because they don’t have the guts. I told my computer I needed a break… Now it won’t stop sending me vacation ads. Parallel lines have so much in common. It’s a shame they’ll never meet. What do you call a fish wearing a bowtie? Sofishticated.

    Claude Opus 5.5: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything. I told my wife she was drawing her eyebrows too high. She looked surprised. Why did the scarecrow win an award? Because he was outstanding in his field. I'm reading a book about anti-gravity. It's impossible to put down.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    ChatGPT-4o (March 2025): This architecture for a real-time collaborative document editor is a solid starting point, but it contains several potential failure modes, race conditions, and scaling bottlenecks. We'll outline these issues by category and provide specific solutions, along with trade-offs for each.

    Claude Opus 5.5: Architecture Review: Real-Time Collaborative Editor The most serious problems cluster in three areas: the sync model (client-clock LWW), cross-server propagation (per-server WebSockets with DB polling), and the CDN/auth layer, which can leak data between users. Issues are grouped by area below.

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    ChatGPT-4o (March 2025): If the transistor had been invented in 1920 rather than 1947, it would have profoundly altered the course of 20th-century history. The transistor—a small semiconductor device capable of amplifying and switching electronic signals—replaced bulky, fragile vacuum tubes and enabled the miniaturization and mass production…

    Claude Opus 5.5: The Transistor in 1920: A Counterfactual Through 1980 First, a Reality Check on the Premise A transistor "invented" in 1920 would not have changed the world in 1920. The actual 1947 transistor rested on three foundations that did not exist yet: Quantum theory of solids.

    Every model's answer to this prompt
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    ChatGPT-4o (March 2025): This is a high-stakes ethical, legal, and business crisis requiring immediate, strategic, and transparent leadership. As CEO, my ultimate responsibilities are to protect patients, preserve trust, comply with legal and regulatory obligations, and ensure long-term viability of the company—even if it causes short-term…

    Claude Opus 5.5: The Next 48 Hours: CEO Action Plan The Core Decision We disclose. The question is how to do it well, not whether. Before the schedule, here are the three facts that drive every decision below. 1. The harm is concrete.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    ChatGPT-4o (March 2025): Certainly! Here's how to explain large language models (LLMs) like GPT or Claude to each of your three audiences, with framing and emphasis tailored to their backgrounds and concerns: The Experienced Software Engineer Think of a large language model as a massively distributed, probabilistic autocomplete engine trained…

    Claude Opus 5.5: How Large Language Models Work: Three Explanations For the Experienced Software Engineer Think of an LLM as a single, very large pure function: f(tokens[0..n]) → probability distribution over tokens[n+1]. Text is chunked into tokens (roughly word fragments, from a vocabulary of about 100k).

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    ChatGPT-4o (March 2025): Here are the three weakest claims in the MindMeld AI pitch deck, along with explanations of why they are weak and suggestions for improving them: 🟠 Weak Claim 1: Slide 1 – Vision Quote: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.”

    Claude Opus 5.5: The 3 Weakest Claims in the MindMeld AI Pitch "Decodes neural patterns into text with 94% accuracy. Works with any language, any device." (Slide 3) Why it's weak: It far exceeds the published state of the art. The best results for thought-to-text come from invasive implants.

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    ChatGPT-4o (March 2025): Absolutely! Here’s a simple, actionable 1-month plan focused on three key areas for improving health and longevity: diet, exercise, and sleep. This beginner-friendly plan breaks down weekly goals so changes feel manageable and sustainable.

    Claude Opus 5.5: Your 1-Month Starter Plan for Better Health & Longevity The philosophy: Small, consistent changes beat dramatic overhauls. Each week builds on the last, so by Day 30 you'll have a foundation of habits instead of a burned-out resolution.

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    ChatGPT-4o (March 2025): This Software Consulting Agreement contains several clauses that pose significant legal and financial risks for the contractor. Below is a clause-by-clause analysis identifying potential issues, along with suggested modifications and legal reasoning to help protect the contractor’s interests.

    Claude Opus 5.5: Contractor-Side Review of the Software Consulting Agreement Overall assessment: This agreement is heavily one-sided. Nearly every clause shifts risk, cost, or control to the Contractor, and several provisions interact to create compounding exposure.

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    ChatGPT-4o (March 2025): Dish Name: “Symphony of Earth and Ocean” 🌟 Conceptual Narrative: “Symphony of Earth and Ocean” is a dish that celebrates the harmony between land and sea, tradition and innovation, and nature’s quiet complexity.

    Claude Opus 5.5: "Hive & Tide" Langoustine, Beeswax, White Chocolate & Oscietra Caviar, Hay-Baked Celeriac, Fermented Green Strawberry, Sea Buckthorn I. The Concept Most coastal menus celebrate the meeting of sea and land. This dish is about a stranger, quieter meeting: the meadow and the seabed, the bee and the langoustine.

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    ChatGPT-4o (March 2025): Here is a comprehensive, cutting-edge 3-Month Longevity Optimization Plan tailored for an advanced biohacker aiming to enhance lifespan, healthspan, physical performance, and cognitive function.

    Claude Opus 5.5: The 90-Day Longevity & Performance Protocol A structured, measurable plan for the experienced biohacker How to Use This Plan Philosophy: Measure → Intervene → Re-measure. Every intervention has a hypothesis, a metric, and a decision rule.

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Same pick

Game

ChatGPT-4o (March 2025)ChatGPT-4o (March 2025)

The Matrix

1999

Dark Side Of The Moon

suisside

Братья Карамазовы

Fiódor Dostoievski

Kyoto

Japan

The Legend of Zelda: Breath of the Wild

Adventure, Action

Claude Opus 5.5Claude Opus 5.5

2001: A Space Odyssey

1968

Kind of Blue

Miles Davis

Gödel, Escher, Bach

Douglas R. Hofstadter

Kyoto

Japan

Outer Wilds

Indie, Adventure

Price and specs

ChatGPT-4o (March 2025) and Claude Opus 5.5 compared across 32 shared prompts
SpecChatGPT-4o (March 2025)Claude Opus 5.5
Input price$5/M tokens$4/M tokens
Output price$15/M tokens$20/M tokens
Context window128K tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedMar 2025Sep 2026
At 10M a month$50.00$50.00$40.00$40.00
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it4 hosts
ChatGPT-4o (March 2025)

No hosts listed on OpenRouter.

Claude Opus 5.54 hosts
HostInOutContextUptime
  • Amazon Bedrock$4.00 in·$20.00 out·1M·93.2% up
  • Azure AI Foundry$4.00 in·$20.00 out·1M·100% up
  • Anthropic$4.00 in·$20.00 out·1M·99.9% up
  • Google Vertex AI$4.00 in·$20.00 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 7 Oct 2026.

Common questions

What is the difference between ChatGPT-4o (March 2025) and Claude Opus 5.5?

ChatGPT-4o (March 2025) is developed by OpenAI while Claude Opus 5.5 is developed by Anthropic. ChatGPT-4o (March 2025) has a 128K token context window vs Claude Opus 5.5's 1.0M. You can compare their actual outputs across 32 challenges on Rival to see how they differ in practice.

Which is better, ChatGPT-4o (March 2025) or Claude Opus 5.5?

It depends on your use case. ChatGPT-4o (March 2025) and Claude Opus 5.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 32 challenges so you can judge which fits your needs best.

How much does ChatGPT-4o (March 2025) cost compared to Claude Opus 5.5?

ChatGPT-4o (March 2025) costs $5/M input tokens and Claude Opus 5.5 costs $4/M input tokens. Claude Opus 5.5 is $1.00/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare ChatGPT-4o (March 2025) and Claude Opus 5.5 on Rival?

This page shows a side-by-side comparison of ChatGPT-4o (March 2025) and Claude Opus 5.5 across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

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Same lab, same size, long tail

  • ChatGPT-4o (March 2025) vs GPT-6 Luna ProSame lab
  • ChatGPT-4o (March 2025) vs GPT-6 Sol ProSame lab
  • Claude Opus 5.5 vs Claude Fable 5.1Same lab
  • Claude Opus 5.5 vs Claude Opus 5Same lab
  • ChatGPT-4o (March 2025) vs Seed 2.0 LiteNew provider
  • ChatGPT-4o (March 2025) vs Seed 2.1 TurboNew provider
  • Claude Opus 5.5 vs Sherlock Dash AlphaNew provider
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Model pages

  • ChatGPT-4o (March 2025)33 outputs, specs and price
  • Claude Opus 5.558 outputs, specs and price
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